NAME:
surfacemass
PURPOSE:
calculate the surface-mass at R by marginalizing over velocity
INPUT:
R - radius at which to calculate the surfacemass density (/ro)
OPTIONAL INPUT:
nsigma - number of sigma to integrate the velocities over
KEYWORDS:
romberg - if True, use a romberg integrator (default: False)
OUTPUT:
surface mass at R
HISTORY:
2010-03-XX - Written - Bovy (NYU)